1. Field of the Invention
The present invention relates to circuit interrupters and in particular to a system for monitoring a circuit breaker wherein data is collected and wirelessly communicated to a separately located receiving device.
2. Background Information
Molded case circuit breakers are well known in the art as exemplified by U.S. Pat. Nos. 6,747,534 and 6,140,897, owned by the assignee hereof, the disclosures of which are incorporated herein by reference. Molded case circuit breakers include a set of separable main contacts, one of which is usually fixed and one of which is movable for automatically opening upon the occurrence of an overload or short circuit electrical current in the network which the circuit breaker is provided to protect. In addition, electronic molded case circuit breakers have trip units, which are often removeably insertable in the circuit breaker case. A trip unit includes a microprocessor, such as a microcontroller, and is adapted to automatically open the circuit breaker contacts under certain conditions. One such condition is what is known as short tripping of the circuit breaker, and occurs when the amount of current flowing through the separable main contacts of the circuit breaker is so high as to represent a potential catastrophic failure and which therefore requires exceedingly quick opening action of the circuit breaker. A second condition is what is known as long tripping, and occurs in response to a relatively low amount of overload current, which eventually will cause overheating of the electrical wires in the circuit to be protected, but which does not necessitate the instantaneous action a short circuit requires and thus does not require the magnetic tripping described above. In either case, one or more current transducers measure the current flowing through the breaker, and the measured currents are provided to the trip unit microprocessor. Algorithms executed by the microprocessor analyze the measured currents and, when a short trip or long trip condition is detected, the microprocessor causes an actuator to open the contacts and thus trip the breaker. Other types of tripping conditions are also known in the art, such as ground fault tripping and over temperature tripping.
Furthermore, it is desirable to be able to monitor certain conditions of a circuit breaker such as a molded case circuit breaker during operation. Such conditions may include, without limitation, causes of trips, breaker temperature, and phase current magnitudes. Typically, a number of molded case circuit breakers, such as 16 or more, are mounted in a single panel. In such situations, it is cost prohibitive and an inefficient use of space to run wires from the breakers to a central location on the panel or elsewhere to transfer the monitored data for subsequent use. Thus, there is a need for a relatively inexpensive and efficient device and system for monitoring certain breaker conditions.